Evaluation of the Impact of Dietary Education and Intervention on Gout Patients Receiving Urate-Lowering Therapy

Gout is becoming more common in Korea. The number of people treated for gout grew from about 220,000 in 2010 to about 300,000 in 2014. This is an average increase of about 8.5% each year. Hyperuricemia is considered the direct cause of gout. Hyperuricemia also appears to be becoming more common. Its average rate rose from 23.9% in 2021 to 26.7% in 2024. Young men appear to be affected the most. Men in their 20s had a rate of 43.8%. Men in their 30s had a rate of 45.7%. These are the highest rates of any age group. This suggests that hyperuricemia is rising fastest among young men. It also suggests that habits such as drinking alcohol and poor diet may need to improve.

Hyperuricemia and gout are known to raise the risk of several chronic diseases. These include high blood pressure, diabetes, and kidney disease. Chronic diseases need ongoing treatment and management. Diets have been developed to help manage symptoms in several conditions, such as diabetes, hyperkalemia, and high blood pressure. However, diets designed specifically for gout patients appear to be limited. So far, the low-purine diet is the only diet known to directly affect blood uric acid levels. However, the low-purine diet can be hard to follow within a typical Korean diet. It also appears to have low long-term sustainability. For this reason, this study modified the low-purine diet into a version that is easier to follow in daily life. This modified diet is called the low-uric acid diet.

The standard low-purine diet usually limits purine intake to 150 mg or less per day. It limits protein from meat, fish, and tofu, and it also limits fat intake. In contrast, the low-uric acid diet used in this study sets purine intake between 300 mg and 400 mg per day. This diet also includes the following recommendations. Participants are encouraged to drink at least 1.5 liters of water per day. Participants are encouraged to have one serving of low-fat dairy per day. Participants are encouraged to eat poultry and fish instead of red meat and organ meats. Among fish, participants are encouraged to choose white fish over oily fish. Participants are encouraged to eat vegetables and fruit at least once per day, and to eat berries regularly. Participants are encouraged to choose plant protein over animal protein. Participants are encouraged to eat whole grains or mixed grains instead of refined white rice. Participants are asked to limit drinks with high-fructose corn syrup or added fructose. Participants are also asked to strictly limit alcohol.

Inclusion Criteria

1. Currently receiving urate-lowering therapy at this hospital
2. Male, aged 19 years or older, with a history of at least one gout flare

Exclusion Criteria

1. Unwilling or unable to provide informed consent
2. Life expectancy of less than 2years due to comorbid conditions
3. Refusal of urate-lowering therapy
4. Estimated glomerular filtration rate (eGFR) of 45 mL/min/1.73m² or less (diagnosed with chronic kidney disease stage 3B or higher)
5. Diagnosis of chronic obstructive pulmonary disease (COPD) or asthma within the past 6 months
6. History of gastrointestinal disease (including inflammatory bowel disease, malabsorption, gastric bypass surgery, or major bowel resection)
7. Currently receiving chemotherapy for cancer treatment
8. Diagnosis of myocardial infarction, heart failure, or angina, or history of coronary artery bypass surgery or angioplasty, within the past 6 months
9. Any other condition that, in the investigator's judgment, makes the participant unsuitable for this study

The primary endpoints of this study are as follows:

• Achievement of target serum uric acid level (<6 mg/dL)
• Reduction in frequency of gout flares
• Increase in dosage of urate-lowering therapy
• Improvement in composite outcome for ASCVD (atherosclerotic cardiovascular disease)

The secondary endpoints are as follows:

• Improvement in BMI
• Improvement in TyG index
• Change in serum uric acid (SUA)
• Improvement in SBP/DBP
• Improvement in HbA1c
• Improvement in intake of purine-rich foods
• Improvement in the number of metabolic syndrome components
• Rate of achieving gout remission, defined as: (1) no gout flares for 12 months; (2) serum uric acid level maintained below 6.0 mg/dL at two consecutive visits (or an average below 6.0 mg/dL over the most recent 6 months); and (3) absence of clinical tophi

Primary and secondary endpoints will be measured every 6 months from baseline. Follow-up visits will use a 3-month window, based on participant scheduling needs.

The Dietary Compliance Questionnaire and the Medication Adherence Report Scale (MARS-5) will be administered continuously throughout the study period for Groups B and C. The REAP-S questionnaire will also be used to assess the objectivity of these measures. FEUA (fractional excretion of uric acid) will be measured once during the study period.

This study includes a total of 4 repeated measurements over 2 years. Comparisons will include within-person comparisons, in which the same participant's data are compared over time (for example, A0001 at screening versus A0001 at 24 months). Comparisons will also include between-group comparisons of mean values.

As an exception, analyses will be conducted both including and excluding participants weighing more than 100 kg. Use of weight-loss injections or oral medications, such as Saxenda, Wegovy, and Mounjaro, will also be collected as a variable. An additional sensitivity analysis will be conducted based on this variable.